JPH0623717A - Reinforced wooden board - Google Patents

Abstract

PURPOSE:To suppress the lowering of impact strength generated by the formalization treatment of a wooden board so as to solve such a problem that the wooden board itself becomes hard and brittle by formalization treatment performed in order to enhance the wet physical properties and dimensional stability of the board and impact resistance lowers. CONSTITUTION:When a wooden board is molded by heating and pressing wood fibers or chips, a synthetic fiber raw material hard to formalize is mixed with a wooden raw material in a wt. ratio of 5-50% and the resulting mixture is formed as it is or mixtures changed in the compounding ratio of the synthetic fiber raw material in the wooden raw material are formed into layers 1, 2 in a thickness direction and these layers are heated and pressed to form a board which is, in turn, formalized by a proper method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention utilizes the porosity of fiberboard, particleboard, etc., in which the dimensional change due to absorption and dehydration is small and the rigidity when wet is maintained so that the strength and dimensional stability are not deteriorated. And improved wood board.

[0002]

2. Description of the Related Art Generally, medium density fiberboard and particle board (hereinafter simply referred to as "wood board")
In the above, the board was stretched, shrunk or swelled due to moisture, water, or drying, and the size of the board was greatly changed. Especially, when the board was wet, the physical properties of the board were remarkably deteriorated. Therefore, when using such a wooden board, there is a problem that the application is limited because troubles often occur due to them.

In order to solve such a problem, the inventors of the present invention focused on the porosity of a wood board thermocompressed to a constant density, and made the front and back surface layers or the inside thereof uniform in a short time. In addition, a method for producing a wooden board that can be subjected to a formalization treatment to prevent deterioration of physical properties when wet and surely improve dimensional stability was filed as a patent application as Japanese Patent Application No. 3-86058.

[0004] The content of the board material is obtained by disintegrating wood into fibrous material or crushing it into shavings or powder granules, applying an adhesive to the board raw material, and heat-pressing / plate-making it to a density of 0.2-0. A wood board of 9 g / cm ³ was set, and the board was set by cutting it vertically in the gas circulation system reactor, and a mixed gas of formaldehyde source such as trioxane, tetraoxane, paraformaldehyde and sulfur dioxide was mixed in the gas phase in the apparatus. Then, the gas is penetrated to the front and back layers or the inside of the wooden board to perform a formalization treatment.

[0005]

However, since the reinforced wood board obtained by the above-mentioned production method is entirely composed of wood fibers or wood chips of the same quality, both sides of the reinforced wood board are subjected to the formalization treatment. The mixed gas penetrating in the thickness direction of the board reacts and reacts and is uniformly processed. Even when only the front and back surfaces of the wood board are formalized, it is extremely difficult to control the permeation range (depth) of the mixed gas that permeates into the porous wood board, and it is formalized to a considerable depth. It was inevitable to be done.

On the other hand, formalization by paying attention to the porosity of the wooden board is a very effective strengthening means for improving the physical properties of the wooden board when it is wet, and for improving the dimensional stability. When the treatment is applied to the whole or a considerable depth of the wooden board, although some effect can be obtained, it is hardened and becomes brittle, so that there is a problem that impact resistance is lowered.

An object of the present invention is to improve the physical properties and dimensional stability obtained by the formalization treatment of a wooden board, and to suppress the decrease in impact strength caused thereby.

[0008]

In order to achieve the above-mentioned object, the present invention always mixes 5 to 50% by weight of synthetic fiber in the wood fiber or shavings as a raw material of this seed wood board. By the method, forming and heat-pressed plates were formed, and a formalization treatment was performed by an appropriate method.

Further, the mixing ratio of the synthetic fibers in the above raw material is
A means of making a layered change in the thickness direction of the board was also used.

[0010]

In the reinforced wood board according to the present invention, the wood raw material is mixed with the synthetic fiber which is difficult to be formalized.
By the formalization treatment applied to the board, it is possible to impart the desired physical properties to the wood part by the formalization, but since the synthetic fiber part in contact with the same mixed gas does not show the formalization effect, this kind of wood board It has a special effect of limiting hardening and greatly improving impact resistance.

In addition, it is recognized that when the synthetic fiber is mixed into the wood raw material and the composition ratio is changed to form a layered structure of high and low layers, the bending strength of the board is improved.

[0012]

EXAMPLES The constitution of the present invention will be described in more detail below with reference to Examples 1 and 2.

Example 1 As a synthetic fiber raw material made of a material which is difficult to be formalized with respect to 100 parts by weight of a wood raw material,
For example, 10 parts by weight of polyester fibers are mixed evenly, without applying or applying a synthetic resin adhesive,
Homing is carried out in accordance with the usual method, and after hot pressing, a mixed gas of the formaldehyde source and sulfur dioxide described below is introduced into the equipment, and the mixed gas is allowed to penetrate to the inside of the board to formalize only the wood raw material part. It has been processed.

In the examples of the present invention, the wood raw material means a material obtained by crushing timber into shavings or powder granules, or further defibrating the wood to obtain a fibrous material. The tree species may be either a coniferous tree or a broad-leaved tree, and the crushed and defibrated state (thickness, length, etc.) is not particularly limited as long as it can be used for ordinary wood boards.

As the material of the synthetic fiber to be mixed,
In addition to the polyester fibers of the above example, PVA-based, acrylic resin-based, polyolefin-based, etc. may be used as long as they are difficult to be formalized by contact with the mixed gas used, and the thickness of the synthetic fiber is usually 2 to 5 denier, long. A size of about 5 to 10 mm is suitable.

Further, as the adhesive to be used, besides urea resin type, melamine resin type, phenol resin type and their co-condensed resins, isocyanate type and epoxy type emulsions (above, thermosetting), EVA -Based, vinyl acetate-based, or acrylic emulsion (above thermoplastic)
It is selected according to the purpose of use of the wooden board.

Example 2 In FIG. 1, reference numeral 1 is a high wood raw material layer forming the front and back layers of the board of the present invention, and a synthetic fiber 7 having the same properties as the above example per 100 parts by weight of wood fiber. It is an even mixture of parts by weight. Reference numeral 2 is a low wood raw material layer which constitutes the core layer of the board, and is obtained by uniformly mixing 100 parts by weight of wood fibers with 40 parts by weight of synthetic fibers which are difficult to be formalized as described above.

Both fiberboards having different blending ratios are separately preliminarily laminated and then polymerized and adhered to each other, or they are simultaneously heat-pressed and laminated as a layered mat during homing, The entire interior is formalized by the mixed gas.

In any of the above examples, if the compounding ratio (weight) of the synthetic fiber to the wood fiber exceeds 50%, the effect of improving the physical properties and dimensional stability of the board due to the formalization of the wood fiber tends to decrease. The impact resistance was not expected to be improved even when it was less than 5%, so the blending ratio of both fibers is preferably limited to the range of 5 to 50%.

[0020]

As described above, the reinforced wood board of the present invention, which has been described in detail above, has a physical property that the wood raw material portion is formalized to strengthen the whole board, and the dimensional change due to inhalation / release of moisture or water is increased. Since it hardly occurs, it is suitable for use in places where moisture resistance and water resistance are required, and since the compounded synthetic fiber part is not formalized, it strengthens the impact resistance by supplementing the physical properties of the board which becomes fragile due to formalization. This enabled the production of wooden boards. Therefore, it has a remarkable effect that the use of this seed wood board can be further expanded.

Further, among the reinforced wood boards according to the present invention, those composed of high and low wood raw material layers in which the compounding ratio is changed are found to have not only impact resistance but also excellent bending strength. Since the boards of the present invention can be formed by the usual homing apparatus and press conditions for this kind of boards, there is no need to change the factory equipment or the like, and there is a great advantage that they can be obtained economically.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a wooden board according to the present invention.

[Explanation of symbols]

 1 High wood raw material layer 2 Low wood raw material layer

Claims (2)

[Claims] 1. When forming a wood board by heat-pressing wood fibers or shavings, a synthetic raw material of 5 to 50% by weight, which is hard to be formalized, is mixed with a raw material of wood to perform forming and forming by a conventional method. A reinforced wood board, which is obtained by heat-pressing and formalizing it by an appropriate method. 2. The blending ratio of the synthetic fiber raw material in the wood raw material
The reinforced wood board according to claim 1, wherein changes are made in layers in the thickness direction of the board.